I'd say both !
I'l try to explain that :
There are plenty of things that you won't really whange in your personnality, because that's just the way you are ! In that way, you have to find people that will accept you as you are, because changing those parts would mean you're no more yourself.
But you are also doing / saying things in order to get people's attention, you know what i mean ? Those can even be bad habits, but they don't define what/who you are, they are just tools you "use" to get something/someone, and those could be changed by the people sourrounding you without changing your true self. So friends could try to make you evolve on those parts without changing the real you, that's just help and it's welcome.
Another part, the easy one : you often meet people because of your interests, but that will change. You don't still like the music you liked when you were 14 years old right ? Or you happen to like things you didn't care / liked years before. Same for food, movies, political thinking, etc. So you're evolving as a human being and thinking. But in most of times you will still remain friends because the bound between you and them has enough strength to overcome those differencies or evolutions. You might loose a fiew friends, but most of them will still love you. So what was common and led you to meet people could change without meaning you have to loose those friendship as soon as the similarities within you are gone.
Now the hard part : we also have vices that can be a wall between us and other people. In the contrary it can also be the way that made you meet them. Drugs, sex practises, religious activities, alcohol, sport, need for adrenaline, stealing, lies you tell, mental troubles, anger, lonelyness, name what you want, friends won't judge too hardly : if they know you, they know why you're in them, or at least they know you do it. But that doesn't mean they totally accept it, and they will want you to change. Some will be able to help you. Some won't but will remain friends and suffer from seeing you like that. Some won't be able to continue on accepting that and will stop seeing you, some will even hurt your feelings by trying to make you change. even if it can feel bad, it's still an act of love / friendship. If i can lead you to think about what you do, why you do it, and how people around you feel about it, you may change. Or not. But you'll be thinking about it, and may be able to name one of your problems or bad habit. You might even want to change, even if you fail. Huge changes take years to happen, and the path is sometimes hard.
Conclusion is : there are no recipe for friendship or love, you have to open your heart and accept the differencies between each others. Once done, you're all ready to recieve what people have to offer : their culture, tastes, experiences, love, anger, suffers, all of them are moments you'll share, and will define who you are and through what you've been. So friends should accept who you are, and are welcome to try to change parts of yourself. By the way : while doing it, they will also change themselves a bit, and you'll also accept them for what they think / do. Would those precious friends still be as valuable / interesting if you totally changed them ? Of course not, just work on the part that could make those person better, even if it doesn't work : they will at least see you care about them :P
Quite a messy answer, right ?