If the firing came after you asked for the accommodation, you have a very possible case of employment discrimination under the ADA, and you should follow up with an attorney experienced in this area of the law.

I can't say whether your request would be considered a reasonable accommodation in court.  It's a flexible concept, with the relief to the worker from their condition being weighed against the inconvenience and cost to the employer, and it can't interfere much at all with getting the work done.  The outcome of this aspect of your case, like the rest of it, will be very fact-sensitive.