Update query.rb

Do not invalidate for operators that only need one of several values to be non-blank.

app/models/query.rb

@@ -95,7 +95,7 @@ def validate
     filters.each_key do |field|
       errors.add label_for(field), :blank unless
           # filter requires one or more values
-          (values_for(field) and !values_for(field).first.blank?) or
+          (values_for(field) and !values_for(field).all?(&:blank?)) or
           # filter doesn't require any value
           ["o", "c", "!*", "*", "t", "w"].include? operator_for(field)
     end if filters