In 4.6c, use IN operator in IF statement when we are having few values

I am trying to use IN operator inspite of IF with OR operator. But the IN opereator is not working with the value, please suggest me how to improve this code

IF v_zuonr(3) EQ 500

OR v_zuonr(3) EQ 551

OR v_zuonr(3) EQ 562

OR v_zuonr(3) EQ 593

OR v_zuonr(3) EQ 594

OR v_zuonr(3) EQ 605.

v_final = v_sgtxt.

ELSE.

v_1 = v_sgtxt(6).

v_2 = v_sgtxt+6(24).

CONCATENATE v_1 v_2 INTO v_final SEPARATED BY space.

ENDIF.