account mgmt

hi - i am using the crm to manage my clients businesses and contacts. The nature of my business is advertising and hence collecting payments from clients on a regular basis. i want to be able to keep track of monthly payments made by each 'account' and compile a report at end of specified period. I can't seem to be able design such a configuration and if i add simple custom fields with payment info, they are not searcheable...Is there a solution to this?
ryan