Assuming you're referring to Microsoft's Remote Desktop Connection Client for Windows, here are some general steps you can follow:
You may need to install the Platform Update for Windows 7 (KB2670838) before this client will function properly. remotedesktop-1.2.790.0-x64.msi download
If you are looking to download this specific installer, please be aware of the following official lifecycle changes from Microsoft : remotedesktop-1.2.790.0-x64.msi download
Corrupt .NET Framework or pending Windows Update. Solution: remotedesktop-1.2.790.0-x64.msi download