Let’s presume that your client is for some reason either unable or simply deciding on paying in instalments to you and not the full amount owed in single payment. There could be various reasons, i.e. managing cash flows of the entity and yet wanting to meat the deadlines or simply negligence from their part. 

How would you recognize such payments however? Provided you’ve been in contact with the client and you know why such a situation arises, you could opt for two choices: 1) receiving one full payment at a later date, resulting in effectively agreeing on longer payment terms; or 2) asking for partial payments to ensure your own cash flows stay afloat some how. It does depend on your own opportunities and your own cash needs to mee your own deadlines with your suppliers.

If you opt for a partial payment, in your accounting you’d also credit the receivables partly, equal to the amount paid by the customer. You could also collect those payments to an account once the receivable is fully paid and only then credit the receivable amount, but to be honest, I personally don’t see the need to mess things up. You’d then have to keep track on the initial balance, the payments and once paid in full, make the entry whereas you could make entries as the payments are transferred to your bank account and once it’s fully paid, just be done with the balance. Entirely up to you of course.