T.H.
Some children speak "their own language" until this age,and then start speaking normally on their own. but it would be wise to get a speech and language evaluation, as his speech is delayed.
The school district in which you live should do an evaluation even though he is not yet school age. If they can't arrange it soon - and with summer coming, I don't know what is possible, you may need to go the private route. I wouldn't wait; if there is a problem detected, the sooner he gets into speech therapy the better. Good luck.
A little about me: Child psychiatrist in practice 16 years; married 21 years with two kids ages 19 and 13.