It depends. The verb 'to be' can be tricky for a non-speaker to understand. If you mean that you are happy having the person in your life then you mean: "Sou feliz com você."
Now, if something that someone did made you happy, then you mean: "Estou feliz com você."
If this is still unclear, let me know what is the context you mean and I'll advise you better. Good luck.
The correct way to say Happy Birthday to someone who speaks European Portuguese is as follows. Say "Feliz aniversario." That means Happy Birthday in Portuguese.
You say "feliz".
"Feliz dia da mãe."
"Happy Anniversary" in Portuguese is "Feliz Aniversario", the same as in Spanish.
Feliz.
Feliz Aniversário!
Felizes Férias.
Felizes Férias.
Feliz Aniversário
"feliz aniversário"
Feliz Sabado
Feliz aposentadoria.