diff --git a/modules/restapi/src/main/resources/docspell-openapi.yml b/modules/restapi/src/main/resources/docspell-openapi.yml
index 7319e878..bff39091 100644
--- a/modules/restapi/src/main/resources/docspell-openapi.yml
+++ b/modules/restapi/src/main/resources/docspell-openapi.yml
@@ -1299,6 +1299,10 @@ paths:
 
         The `fulltext` field can be used to restrict the results by
         using full-text search in the documents contents.
+
+        The customfields used in the search query are allowed to be
+        specified by either field id or field name. The values may
+        contain the wildcard `*` at beginning or end.
       security:
         - authTokenHeader: []
       requestBody:
@@ -1920,7 +1924,8 @@ paths:
       summary: Set the value of a custom field.
       description: |
         Sets the value for a custom field to this item. If a value
-        already exists, it is overwritten.
+        already exists, it is overwritten. A value must comply to the
+        type of the associated field. It must not be the empty string.
       security:
         - authTokenHeader: []
       parameters:
@@ -2389,7 +2394,9 @@ paths:
       summary: Set the value of a custom field for multiple items
       description: |
         Sets the value for a custom field to multiple given items. If
-        a value already exists, it is overwritten.
+        a value already exists, it is overwritten. The value must
+        comply to the associated field type. It must not be the empty
+        string.
       security:
         - authTokenHeader: []
       requestBody:
diff --git a/modules/store/src/main/scala/docspell/store/queries/QItem.scala b/modules/store/src/main/scala/docspell/store/queries/QItem.scala
index a742547a..4252d590 100644
--- a/modules/store/src/main/scala/docspell/store/queries/QItem.scala
+++ b/modules/store/src/main/scala/docspell/store/queries/QItem.scala
@@ -289,7 +289,7 @@ object QItem {
         and(
           cfColl.is(coll),
           or(cfName.is(v.field), cfId.is(v.field)),
-          cvValue.is(v.value)
+          cvValue.lowerLike(QueryWildcard(v.value.toLowerCase))
         )
       )
     if (cv.isEmpty) Seq.empty