References when my manager was laid off too after 16 years as an accountant

My manager was laid off too and I am unsure who to use as a reference. I am in Omaha, in case local advice matters. A colleague offered to vouch for me. Is a client acceptable?

Thanks for writing this out. I went through something close to it 3 months ago, and it got easier once I kept a simple log of every call and form.