When you say 'search box' is this the quick find box in the toolbar or a search box you created. If the fields are set up to allow Quick Find, then searching in the toolbar's quick find box will find the data.
Keep in mind if you are on a record, say John Smith, go into a portal on the record and search for a date, the find will show all the parent records that have any portal records with the same date.
So if wish to avoid that, you will need a more complex search script. In this case you would want to have your own search box. Then you can either trigger the script with OnObjectModify script trigger, or put a button next to the box to perform the script.
You could also filter the portal, or use another portal with the filtered relationship, but I think if you have a lot of portal records this may be slower.
Actually, if you click into that portal of expenses, and type values such as 12/17, coffee, delicious into date, description and note (respectively), you'll only find records where a related record has 12/17, coffee AND delicious. (You won't for instance, find records where one expense was on 12/17, another was for coffee, and another has the note "delicious".)
Not sure if this is what you're asking, but it sounds as though you might be, and I, for one, found this surprising and useful when I figured it out.
Double click on your portal and choose to filter.
your search box field = xSearch (global)
In the table of your portal, create a calculation field: Calc = Description & " " & Notes
In your Filter:
Case ( not IsEmpty ( xSearch ) ; PatternCount ( Calc ; xSearch ) > 0 ; "" )
Can you please take a look with attache image.
Its custom search box for portal, which I'm going to search any of the column (note1, note2, note3). for example sometime I search "PHP", sometime "Recreation" and sometime "Bettroot"
I think we could achieve this via Portal Setup > Filter Portal Records, but I'm struggle to step up