My son was the exact same way and he's only 2 and 1/2. What I did was make him think that school was a fun place to go and have fun. We even put something special in his lunch box each day like a new hot wheels car. I got him really excited about it and when I arrived to pick him up I asked about his day what did he like and what didn't he like. This went for about 2 weeks each day making progress. And BAM !! before you knew it he was telling me without having to ask.
I don't think he is 'acting up'... some are simply stating quite honestly that they don't want to be there and they want to go home. Encouraging him to go to preschool and staying there and being firm about that is one thing, but never think he is being 'rude, bad, out of control'. He is 3. And he is behaving quite normally for a 3 year old. The supervisors and caregivers there need to be more responsible and using their wits to keep them entertained, happy, at ease and compliant. Not always will that happen, but a good preschool usually has bright, happy kids that don't want to go home usually as they are having a great day and are proud of that.
If he continually wants to go home, I would look around for a private home daycare or another arrangement.
Woofy
It is, of course, important that you support the school's expectations and instruct your son to 'stay put' in school and do what the teachers say. Just as important (actually, more important), though, is the response of the school. It is their responsibility to manage the beahvior. It is not hard. They should place your son in time out when he does not comply with directions; they should do the same if he makes any motion to exit the space. There really is no excuse for a three-year-old having the opportunity to leave the building. The supervision has to prevent that.