>That what openquery is for. You can send pass-through query to the specified linked server. Fox is in my case.
>Problem is to build a complete string with parameters. Too many quotes.

If the linked server is Fox and you want to use strings do this:

select * from openquery(VAMCPD,'select a.cItemno,a.nShipQty,a.nSalesAmt-a.nDiscAmt as Amt
                                       from aritrs a
                                inner join arinvc b on a.cInvNo=b.cInvNo
                                where a.cCustno+a.cInvNo like "'+@StringPar+'%" and cType= ""')

this is not tested.
As you see you can use double quotes ub the query string if the linked server accepts them.

You even can use square brackets:

select * from openquery(VAMCPD,'select a.cItemno,a.nShipQty,a.nSalesAmt-a.nDiscAmt as Amt
                                       from aritrs a
                                inner join arinvc b on a.cInvNo=b.cInvNo
                                where a.cCustno+a.cInvNo like ['+@StringPar+'%] and cType= []')