There's no direct equivalent, but there are some methods work similarly, depending on the pattern.
string.Contains("pattern")
is equivalent toLIKE '%pattern%'
string.StartsWith("pattern")
is equivalent toLIKE 'pattern%'
string.EndsWith("pattern")
is equivalent toLIKE '%pattern'
However, in your SQL query the pattern is dynamic, so I don't think there is a good way to convert it straight to Linq. If you know at design time that the pattern fits one of these cases you can use this:
var result =
from claimsRow in context.BaseClaims
let wpId = context.UserProfiles.Single(upRow => upRow.ID == 1459).WPId
where claimsRow.WPId.Contains(wpId) // or StartsWith or EndsWith
select claimsRow;
Or possibly
var wpId =
(from upRow in context.UserProfiles
where upRow.ID == 1459
select upRow.WPId)
.Single();
var result =
from claimsRow in context.BaseClaims
where claimsRow.WPId.Contains(wpId) // or StartsWith or EndsWith
select claimsRow;