You can manually trigger an update of Office Click-to-Run installations, without starting any of the Office applications. This can be useful in VDI-environments where it may be necessary to update Office in the source image.

To trigger the update, start the Click-to-Run client with the /update switch.

Perform the update (will show a progress bar):

"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe" /update user

Silently perform the update (don't show progress bar and force Office apps to restart):

"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe" /update user displaylevel=false forceappshutdown=true

Both commands will tell Office to update itself through the internet using the current channel. You can also change the update channel to something else:

"C:\Program Files\Common Files\Microsoft Shared\ClickToRun\OfficeC2RClient.exe" /changesetting Channel=Current

The current channels are (more info):