You cannot do this in quickbooks. 

1. Go to Reports.
2. Locate in the Search bar the Transaction List with Splits.
3. Click Customize.
4. Under the Rows/Columns, select Customer.
5. In the Filter section, check Transaction Type and select Billable Expense charge and Bill. 
6. Once done, click Run Report.

There is no option to group by customer under rows/columns. Only Nothing, Account, Name, or Transaction type.