Start with speech. Call your local school district. You could go through your pediatrician, but many insurance companies will no longer pay for speech one the child reaches the age of 3.
My youngest has a speech delay. I took him to speech bi-weekly for about a year. It definitely helped. He is 3 1/2 now and in PreK and going to speech through school, and I agree with CAE990210 that going to speech and to school (interacting with peers and teachers) has made a HUGE difference. Some evenings my husband and I look at each other in awe at the words he will use or how clear he speaks.
Last I said, "Oh, oh, skettios!" To which he replied, "Not skettios, sphaghetti-ohs!" Shock and awe!!! I was so proud of him, I almost cried!
I would also agree that there's no reason to worry about the potty training. Many boys will be trained around the age of 3, and that's great. My oldest trained when he was just a couple of months shy of his 4th birthday. It was due, in part, to when we had a nice, long break from preschool and were able to take advantage of down time and just stay home and figure this thing out.
I swear my youngest was potty trained this summer (around 3 1/2). But then he went back to daycare and started PreK, so we're back in pull-ups. I'm hoping to address this again over Christmas break. He had a tough time adjusting to the new schedule, but he's doing great now, so I'm optimistic.
My point in telling you the last two stories about potty training is just that speech and potty training are big, emotional adjustments for kids. It really might be easiest on him (and have a better chance of success) if you tackle them one at a time. Start with speech and go from there.
Good luck!