My solution is based on @marc_s solution, i just concatenated columns in cases that a constraint is based on more than one column:
SELECT
FK.[name] AS ForeignKeyConstraintName
,SCHEMA_NAME(FT.schema_id) + '.' + FT.[name] AS ForeignTable
,STUFF(ForeignColumns.ForeignColumns, 1, 2, '') AS ForeignColumns
,SCHEMA_NAME(RT.schema_id) + '.' + RT.[name] AS ReferencedTable
,STUFF(ReferencedColumns.ReferencedColumns, 1, 2, '') AS ReferencedColumns
FROM
sys.foreign_keys FK
INNER JOIN sys.tables FT
ON FT.object_id = FK.parent_object_id
INNER JOIN sys.tables RT
ON RT.object_id = FK.referenced_object_id
CROSS APPLY
(
SELECT
', ' + iFC.[name] AS [text()]
FROM
sys.foreign_key_columns iFKC
INNER JOIN sys.columns iFC
ON iFC.object_id = iFKC.parent_object_id
AND iFC.column_id = iFKC.parent_column_id
WHERE
iFKC.constraint_object_id = FK.object_id
ORDER BY
iFC.[name]
FOR XML PATH('')
) ForeignColumns (ForeignColumns)
CROSS APPLY
(
SELECT
', ' + iRC.[name]AS [text()]
FROM
sys.foreign_key_columns iFKC
INNER JOIN sys.columns iRC
ON iRC.object_id = iFKC.referenced_object_id
AND iRC.column_id = iFKC.referenced_column_id
WHERE
iFKC.constraint_object_id = FK.object_id
ORDER BY
iRC.[name]
FOR XML PATH('')
) ReferencedColumns (ReferencedColumns)