Free shipping when at least 1 product is checked with a certain attribute

Hello,

I have a shop with 178.000 products. Each product does have either two attributes set (1 and 2) or three (3,4,5).

Now I would like to apply a free shipping if total order amount exceeds a certain amount (fe. > 50 €) OR if a certain product attribute is set (fe. attribute 4) at least once.

In order words:

IF (
total order amount > 50 €
OR
productattribute 4 is set at least once
) {
free shipping
} else {
apply shipping rate
}

How could this be done with standard functionality? With the "table" module, I can achieve the first condition (total amount > 50) but how could I check in the shoppingcart if there is a product with a specific attribute set?

Any suggestions?

Thanks in advance!!!!