Search within collections generate separate subqueries for each field, rather than merging all searches within the collection together.

[ascott18]

Actual:

SELECT COUNT(*)
FROM [UploadedFiles] AS [u]
WHERE (LOWER([u].[OriginalPath]) LIKE @__Value_1_contains ESCAPE N'\' OR EXISTS (
    SELECT 1
    FROM [ProcessingEvents] AS [p]
    LEFT JOIN [Foos] AS [r] ON [p].[FooId] = [r].[Id]
    WHERE [u].[Id] = [p].[ProcessedFileId] AND [r].[Name] IS NOT NULL AND LOWER([r].[Name]) LIKE @__Value_2_contains ESCAPE N'\') OR EXISTS (
    SELECT 1
    FROM [ProcessingEvents] AS [p0]
    LEFT JOIN [Foos] AS [r0] ON [p0].[FooId] = [r0].[Id]
    WHERE [u].[Id] = [p0].[ProcessedFileId] AND [r0].[Code] IS NOT NULL AND LOWER([r0].[Code]) LIKE @__Value_3_contains ESCAPE N'\') OR EXISTS (
    SELECT 1
    FROM [ProcessingEvents] AS [p1]
    LEFT JOIN [Foos] AS [r1] ON [p1].[FooId] = [r1].[Id]
    WHERE [u].[Id] = [p1].[ProcessedFileId] AND [r1].[Description] IS NOT NULL AND LOWER([r1].[Description]) LIKE @__Value_4_contains ESCAPE N'\'))

Desired:

SELECT COUNT(*)
FROM [UploadedFiles] AS [u]
WHERE (LOWER([u].[OriginalPath]) LIKE @__Value_1_contains ESCAPE N'\' OR EXISTS (
    SELECT 1
    FROM [ProcessingEvents] AS [p]
    LEFT JOIN [Foos] AS [r] ON [p].[FooId] = [r].[Id]
    WHERE [u].[Id] = [p].[ProcessedFileId] AND (
	([r].[Name] IS NOT NULL AND LOWER([r].[Name]) LIKE @__Value_2_contains ESCAPE N'\') OR
	([r].[Code] IS NOT NULL AND LOWER([r].[Code]) LIKE @__Value_2_contains ESCAPE N'\') OR
	([r].[Description] IS NOT NULL AND LOWER([r].[Description]) LIKE @__Value_2_contains ESCAPE N'\')
	))