Best way to upgrade clients.

Hi everyone,

My existing SEPM & SEP version is 12.1.2(RU2)

i want to upgrade to 12.1.3(RU3).

I am having 30000+ clients in my enviorment at remote locations.Can anyone suggest the easiest way to upgrade all my clients.

do i need to run push deployment tool for all my clients? any other option.....