You can create a report based on Task Time template, with columns for Client, Project, and Task Name enabled. Apart from these columns you would have to enable the Actual hours column. Finally you can set up Grouping for Client Name which should give your the Summary. However, if you want further detailed Summary, you can enable Grouping of Project Name and Task Name. Once the report has been created and saved, you can set up a schedule with Recurrence set to Weekly.