How to build a multi-input dashboard and ignore inputs that are left blank?

[Glasses]

Hi 

I am trying to build a multi-input textbox dashboard based on a KVstore lookup.

My query is like this

| inputlookup <some-host-detail-kvlookup>
| search $computer_name$ OR $computer_number$ OR $computer_id$
| fields computerName computerNumber ComputerId ... 

each token has a prefix i.e. <fieldName> =  (which is the column header field in the lookup)

each token also has an initial value = null 

thus the query runs like this 

| search computerName=null OR computerNumber=null OR ComputerId=null

| search computerName=FOO  OR computerNumber=null OR ComputerId=null

as you can see setting  the <fieldName> to null allows the search to run without breaking, but after a user enters FOO for the computerName value, they need to reset the blank search inputs back to null.   Otherwise if a blank is passed like 

| search computerName= OR computerNumber=null OR ComputerId=null

the search breaks.

Any suggestions how to ignore the empty inputs or a way to reset the initial values to null again is greatly appreciated.  OR if anyone has a suggestion to do this another way, I would very much like to hear.

Thank you