You need to make sure that your criteria are "OR"d.
Let's say that you have 3 text boxes on your form (txtField1, txtField2, txtField). You'll need three criteria rows in your query, in the column for Field. The first will look like:
[Forms]![fMyFormName]![txtField1]
and the second will be:
[Forms]![fMyFormName]![txtField2]
followed by:
[Forms]![fMyFormName]![txtField3]
Access will "OR" these three fields together. Note that you will need to repeat any criteria for other fields on each row.
If this gets to be too much (more fields than you want to repeat), you might find that you could create a filter or build a WHERE clause more simply.