Hi Patrich,
Welcome to the QuickBooks Community. I'll be happy to share more info so you're on the right path with achieving your goals. The program is designed to help you streamline your work and I'll be glad to point you in the right direction.
QuickBooks allows you to filter your reports by Customer. To do this, open the report in question > click on Customize > under Filter, select the customer in question in the Customer field > hit Run report. For reference, here's a helpful article that shows you how to: Customize reports. Just to confirm, are you looking to add another field on the invoice to the already existing custom fields? You can check out the customizable options available to you using this link here.
Feel free to reach back to me in the comments below. I'll be on standby in case you need anything else.