EXCEL FORMULA HELP

I have a quote form my company uses and I would like to formulate two cells to auto fill the names I have stored on a separate workbook, or if that won't work I have the list on a separate tab on the same work book.

Attached is the Excel sheet I started, I would like Cell B6 to automatically pull up a name off the Client Tab Company List, i.e if I type the Letter "D" then all companies that start with that letter will populate.  Same goes for Cell B7, when I type the letter "A" all clients with the name starting with "A" will populate