The Magic Thief by Sarah Prineas
A street kid is poor and commits minor crimes. He gets in trouble with magic pickpocketing. He becomes apprenticed to a wizard and ends up needing to go to school. He doesn't take well to some of the "false" things taught. He does some adventures (often by being transformed into a cat.) He has some relationship to a bad wizard. Somebody is trying to steal magic to get power. However, the kid feels that magic is alive. It was a little too much fantasy to stay interesting.
