业务SQL中的模糊like条件子句如何才能用上索引？

业务SQL中的模糊like条件子句如何才能用上索引？下面这条SQL没有用上索引，消耗资源极多：

select count(1) countNumber from( select cc.CLAIM_ID,ROWNUM from claimcontract cc INNER JOIN GNTSLIP_EXPAN_INF G ON CC.Contract_Id=G.ARRANGEMENT_ID inner join (select C.CONTRACT_ID from contract c where exists( select 1 from CONTRACTROLE CR where CR.CONTR_COMPONENT_ID = C.CONTRACT_ID and CR.CONT_ID = '' and C.END_DT < SYSDATE AND

            CR.END_REASON_TP_CD IS NULL AND (CR.CONTR_ROLE_TP_CD BETWEEN 1 AND 3)

) AND C.EXECUTED_DT>=ADD_MONTHS(trunc(SYSDATE), -36)) t on cc.contract_id=t.CONTRACT_ID AND (G.GNTSLIP_NO like 'E%' or G.GNTSLIP_NO like 'W%' or G.GNTSLIP_NO like 'P%' ) )