CrudRepository - how to find objects by map key and value

I have problem with "selecting" values using CrudRepository.

For example:

I have Client class:

@Entity
public class Client {

@Id
private Long id;

@ManyToMany
Map<AttributeType, Attribute> map = new HashMap<>();
}

and AttributeType class:

@Entity
public class AttributeType {
    @Id
    private Long id;

    @Column(unique = true)
    private String name;
}

"Attribute" is abstract entity which have "subtypes" of String and Boolean (AttributeBoolean, AttributeString), and both have 2 fields ID, and VAL (which is String val or Boolean val depends on "className").

So, if I want to select client list which have "AttributeType" in map I can use:

public interface ClientRepository extends CrudRepository<Client, Long> {
  @Query("select cli from Client cli where KEY(cli.map) = :attributeType ")
    List<Client> selectByAttributeType(@Param("attributeType ") AttributeType attributeType );
}

But I have problem with "selecting clients which AttributeType equals x and that Attribute equals y".

I was trying to use:

@Query("select cli from Client cli \n" +
            "where KEY(cli.map) = :attributeType \n" +
            "and VALUE(cli.map).val = :val")
List<Client> selectByAttributeTypeAndParam(
@Param("attributeType") AttributeType attributeType, @Param("val") String val);

But it throws exception: Caused by: java.lang.IllegalArgumentException: Parameter value [xxxxxxxx] did not match expected type [java.lang.Boolean (n/a)].

So, the question is: Do you have any idea, how can I select Every Client where: AttributeType = x and value from map (for that AttributeType) = y ?

//edit... To better understund:

We have situation like this:

AttributeType at1 =...  //does not matter what is it
AttributeType at2 =...  //does not matter what is it
AttributeType at3 =...  //does not matter what is it

Client c1 = new Client();
Map<AttributeType, Attribute> map1 = c1.getMap();
map1.put(at1, new AttributeString("123456789");
map1.put(at2, new AttributeBoolean(true);

Client c2 = new Client();
Map<AttributeType, Attribute> map2 = c2.getMap();
map2.put(at1, new AttributeString("111111111");
map2.put(at3, new AttributeBoolean(true);

So, i want CrudRepository function which take 2 parameters.

1) AttributeType 2) SomeValue (can be String or Boolean)

If this function looks like:

@Query("some query - no idea how to write it")
List<Client> selectByAttributeTypeAndParam(
@Param("attributeType") AttributeType attributeType, @Param("val") String val);

and if i run:

List<Client> someList = selectByAttributeTypeAndParam(at1, "12345679");

I want that someList have 1 record which is c1.

And if i have equivalent function for Boolean search and i run:

List<Client> someList = selectByAttributeTypeAndParam(at2, true);

Than i want that someList have both c1 and c2 records.