Get the Servicing Exstension from Microsoft NOW as it does all the work!!! http://blogs.technet.com/b/configmgrteam/archive/2014/12/09/now-available-microsoft-system-center-2012-configuration-manager-servicing-extension.aspx
Once you have this, in the Admin node, there's a site servicing section -> client targeting. You click 'Create Query' and it makes a nice query for your collections.
Then you go about creating your collection.
click next. Select Add Rule -> Query Rule
Click Import Query Statement and choose the nice query microsoft made for you.
Deploy the cumulative update to the clients.