List<List<SObject>> searchList = new List<List<SObject>>();
searchList = [FIND 'TestDataSearchKey' IN ALL FIELDS RETURNING Account(id, Name, pradeep_dani__Preferred_Service__c, pradeep_dani__User_test__r.Name ORDER BY Name DESC NULLS FIRST)];

List<Account> accList = ((List<Account>)searchList[0]);

for(Account a : accList){
    System.debug(a.pradeep_dani__Preferred_Service__c);
}