Try this,
SELECT
n.Caption as [Name]
,'/Orion/View.aspx?View=NodeDetails&netObject=N:' + ToString(n.NodeID) AS [_LinkFor_Name]
,n.IPAddress AS [IP Adress]
,n.CustomProperties.DC_Location AS [Datacenter]
,n.CustomProperties.DC_Rack_Location AS [Location]
,n.CustomProperties.DC_Rack AS [Rack#]
FROM Orion.Nodes n
WHERE
n.Caption LIKE '%${SEARCH_STRING}%'
OR n.IPAddress LIKE '%${SEARCH_STRING}%'
OR n.CustomProperties.DC_Rack_Location LIKE '%${SEARCH_STRING}%'
