What does yo estoy contigo mean?

It's not "Kere" It's "Quiere" (Good try for pronunciation!) But "Quiere yo contigo" is not good Spanish and it does not mean, "I want you", although that is what google translate claims. Literally it mean "you (or he/she) wants I with you"

I want you with me - te quiero conmigo

I want you - te deseo

You say "(Yo) Quiero contigo" to a girl you like. It's a way to tell her you have feelings for her.