Custom Record Field Extracting Partial Date Issue

I am using custom record field to extract completedOnDate (custom field) from completedOn(date and time) field. But there are sceanrio where ,when I am changing time zone ,date returned is still in gmt but not according to user timezone because of this when I am quering like below,few extra work items are displayed
a!queryFilter(
field: 'recordType!{ee5aa46d-0228-430f-a794-1134a11fbcc0}CMGT_Task.fields.{d7e1c9a9-03ae-4bfd-bbe6-2edc7e8d915f}completedOnDate',
operator: "=",
value: today()
),
 How to fix this issue ,so that date is based on user timezone only and not in gmt