Here is another sample:
private void OnFilter(FilteringEventArgs args)
{
args.PreventDefaultAction = true;
var predicate = new List<WhereFilter>();
predicate.Add(new WhereFilter() { Condition = "or", Field = "Code", Operator = "StartsWith", value = "0" });
predicate.Add(new WhereFilter() { Condition = "or", Field = "RoutingNumber", Operator = "StartsWith", value = args.Text });
var whereFilter = WhereFilter.Or(predicate);
var query = new Query().Where(whereFilter).Take(10);
this.RoutingNumberAutocomplete.Filter(this.StandardAchDirectories, query);
}