Most of the dictionaries online do not list 'wanting' as the present participle of 'want'. It just means 'lacking' in general it seems. However some dictionaries do and I am wondering if the 'wanting' is ever actually used as the present participle of 'want'.
As far as I know, every English verb with an infinitive form also has a “gerund-participle” (a single form traditionally called either a "present participle" or a "gerund" depending on its use) formed by adding -ing to the infinitive form (sometimes with certain spelling changes). Because this is such a regular and predictable part of English grammar, many dictionaries may not explicitly list this; others do. When a dictionary does not list this form of a verb, it is not saying that the form does not exist.
The verb want does have a gerund-participle form wanting. Wanting is additionally used as an adjective: the existence and meaning of -ing adjectives is less regular and less predictable than the existence and meaning of -ing verb forms, so dictionaries are more likely to include explanations of -ing adjectives.
The "present participle" is used in the progressive or continuous construction, and also in some other contexts. Some verbs aren't used very often in the progressive, but they still have present participle forms.