Hey, I had to help a relative with something similar last year. Basically, you want to look up local places that sell suits, and ask them how much custom tailoring they do. Many places will only do simple alterations like adjusting the hems to your specific arm or leg lengths. But some places can take a complete set of your measurements and have a custom suit made for you. Just tell them your needs and ask if they can help you. (In our case we were only looking for business suits, but I saw at least one place that did this for business casual too.)

You might be tempted to try to take your own measurements and get something made online by yourself, but in our case we found it hard to know if we were doing the measurements correctly, which is why I suggest finding a place to do them in person.