Experts usually state that Asperger's children talk early and well but are not social with other kids like their peers. I am not an expert but if he is not talking at 3, he probably does not have Asperger syndrom. He might have something else in the PDD spectrum. Asperger's children are like "little professors" when they speak. They do speak well but are not social. They also have extreme interests in certain topics or things. They will, for example, love trains. All they want to do is play with trains, speak about trains and go see trains. They also want a very strict routine. If their routine is changed, they get upset and have tantrums. If his speech is delayed, you need to get an evaluation for him, so that the "expert" doctors can help you with the choice of therapies (speech therapy, OT, social skills classes, behavior modification). If you can not affort the private evaluation, you live in the US and he is turning 3, you need to call your local public school district for help. The school district will need to help you free of charge. Your first step is to see his doctor and obtain a referral to a good child development doctor or psychologist (if you can afford it or have insurance) that can evaluate his current behavior and abilities or he will tell you to call the school district for a free evaluation.
There is no way to tell from your description, but he definitely does display some form of pervasive developmental disorder. He should undergo a developmental evaluation right away. The younger children are when the situation is evaluated the better they respond to intervention.