List out the clients who choose statement of issuance after transaction are Disponent?
'POPLATEK PO OBRATU' stands for issuance after transaction
SELECT T2.client_id FROM account AS T1 INNER JOIN disp AS T2 ON T1.account_id = T2.account_id WHERE T1.frequency = 'POPLATEK PO OBRATU' AND T2.type = 'DISPONENT'