Speaking to others in a different language such as Spanish or Arabic?

How does one say certain American colloquialisms (or something similar which gets the same point across) such as "Take care!" (e.g. a way of saying goodbye after helping someone), and/or more formal phrases such as "Hello, I am/my name is Joe".

I ask because I work in a hospital and it would be nice to interact with certain patients using their first language, at least whilst greeting them and and leaving them, I'd imagine it would make them feel more comfortable. Most patients whose first language is not English either natively speak Spanish, Arabic, or German.

Any and all helpful answers and/or related tips would be very much appreciated.