how to "OR" two filters in record type

Hi there,

I have a record type, want to show the time date either is null or earlier than today. Could anyone here how to combine these two filters together?  

a!queryFilter(
field: 'recordType!{30a8a442-d786-4e84-a096-714b5ce3577a}CPD_peng_test.fields.{countedTime}countedTime',
operator: "is null"
)

a!queryFilter(
field: 'recordType!{30a8a442-d786-4e84-a096-714b5ce3577a}CPD_peng_test.fields.{countedTime}countedTime',
operator: "<",
value: todatetime(today())
)

regards,

Lin