You can, but its not advisable.  It takes many months for those to get through the system, its quicker and less confusing to just have them make a payment now for as much as they can afford, then wait for the first IRS bill, once they have that, the client can create an online account and set it up themselves.   

If you send it with the tax return, they wont hear anything for over 3-4 months and the client will be calling you asking what to do, when are they gonna take the money, etc.