Fizik now have some very wide fitting shoes. I also have fairly wide feet (112 mm x 281 mm) and I find the Fizik R4 Wide is very generous in my size. The toe-box in particular is huge.
Edit: I see you mentioned Shimano. I previously tried their standard fit shoes and they were way too narrow for me. I didn't try their wide fit, but I read that they are not that much wider.