if someone came into your life and he changed you a lot, brings the best of you, how to say it?

"he changed me"

See a translation

"He changed me." would work, but you should probably also give the person you are talking to an example or some details to show more of what you meant, because it is slightly ambiguous if this is a good change or not. And because it is a very short sentence, so it doesn't give very much information. So if you said this in a conversation, people would expect you to then tell them more about it after saying that, so that they can really understand what you meant by it. It doesn't say much by itself.

You could also say:
"He changed my life."
"He made/makes me a better person."
"He inspires me a lot to try harder at things and to be better in general."
"He is a role model for me./ I look up to him a lot. / I admire him a lot."
"He brings out the best in me."
"I'm a better person when he is around."