Well, warmth is generally achieved with frequencies around 200 Hz. Try some subtle boost around there, varying the frequency slightly up and down if you have a parametric. However, don't expect dramatic results.
If you meet a real radio host, you'll realise that they really do have warm, resonant voices. It's not the product of EQ in post production. Unless your voice leans that way naturally, you're probably on a hiding to nothing.
However, to give yourself a chance, you should start practicing using your "chest voice" rather than your "throat voice". Speaking from and with your diaphragm rather than just using your throat/mouth will give you more projection and warmth naturally. Seriously, you'll gain more by changing your vocal technique than you will with EQ.