Download Microsoft Remote Desktop for Mac. Connect to Windows-based PCs to access Windows-based files, applications, devices, and networks from your Mac.
I think you are out of luck, I don;t think you can download it from anywhere else.
Maybe also look into http://cord.sourceforge.net
Why don't you try downloading it on your computer and see if you can extract the file from the download? Right-click and show package content.
PS: Is that: https://www.microsoft.com/en-us/download/details.aspx?id=465 the right client?
I can't test it since I don't have a MAC at work.
Microsoft Remote Desktop Mac Download Without App Store
Microsoft Remote Desktop Mac Download Offline
or this one: https://www.microsoft.com/en-us/download/details.aspx?id=18140
Edited Apr 21, 2015 at 22:53 UTC